Genesis and tectonic implications of Caledonian Dayekou adakite diorite porphyry of Xishui area, Zoulangnanshan, North Qilian Mountain

Geochemical studies of diorite porphyrite in Xishui area of Zoulangnanshan within North Qilian Mountain show that the rock is characterized by SiO₂ > 56%, Al₂O₃ > 15%, Na₂O > K₂O%, LILE and LREE enrichment, positive Eu anomalies, Sr enrichment, depletion of heavy rare earth elements Yb and Y, and higher Sr/Y ratios, showing obvious geochemical characteristics of adakite. Ac-cording to the regional geological study, the authors hold that Dayekou diorite porphyrite was formed in the Caledonian Ordovician period associated with subduction of the oceanic crust partial melting and crust-mantle magma mixing.